RU2818124C1 - Method for experimental simulation of hypothyroidism in laboratory rats - Google Patents

Abstract

FIELD: medicine; experimental medicine.

SUBSTANCE: invention can be used in simulating hypothyroidism in laboratory rats. Method includes maintenance of laboratory rats on a ration with low iodine content in dose of 20 g of the mixture per day individually for each animal for 30 days, followed by the introduction of the preparation "Mercazolil" in dose of 2.5 mg/100 g of live weight for 21 days. Then, during the recovery period, animals are also fed on a diet with low iodine content.

EFFECT: use of the invention enables to achieve hypofunction of the thyroid gland, which is characterized by a decrease in the level of thyroxine and triiodothyronine in the blood and an increase in the level of thyroid-stimulating hormone, as well as preservation of said state in the recovery period after the termination of the administration of the thyreostatic agent to the rats.

1 cl, 3 tbl

Description

The invention relates to the field of veterinary medicine, namely experimental endocrinology, and concerns a method for modeling hypothyroidism in laboratory rats, which will allow the development of new effective methods for the prevention and treatment of this pathology. The method can be used to study the effectiveness of iodine-containing drugs.

Iodine is an essential element in the nutrition of mammals and is part of the thyroid hormones: thyroxine T4 and its active form triiodothyronine T3. Thyroid hormones are involved in the regulation of many physiological processes, including growth and development of the body. Iodine deficiency provokes a decrease in the functions of the thyroid gland, which leads to the development of a disease such as endemic goiter, as well as to stunted growth of young animals, decreased productivity and reproductive function.

There are various methods for experimentally modeling hypothyroidism in laboratory rats. One of these methods is the intragastric administration of thiamazole (mercazolyl) in the form of a water-starch suspension once in a daily dose of 5-50 mg/kg of rat body weight for 21 days (Patent RU 2165 648 C2, published on April 20, 2001). This method allows us to obtain a model of hypothyroidism with the possibility of spontaneous restoration of thyroid function. This does not take into account the intake of iodine into the body of rats along with the standard feeding diet, which contributes to a fairly rapid restoration of thyroid function after stopping the administration of the thyreostatic drug, since the level of iodine content in the body practically does not change with this modeling method. The difference between our proposed method is that rats are kept on a specially developed diet with a low iodine content, which, together with the use of a thyreostatic agent, makes it possible to obtain an effective model of experimental hypothyroidism and minimizes the possibility of spontaneous restoration of thyroid function after stopping the administration of the thyreostatic agent. Thus, this model allows us to obtain the most reliable results when studying the effectiveness of iodine-containing drugs.

The objective of the invention is to develop a new method for experimental modeling of hypothyroidism in laboratory rats, which is the most effective for achieving the desired results.

The technical result of the claimed invention is the occurrence of hypofunction of the thyroid gland in laboratory rats, which is characterized by a decrease in the level of thyroxine and triiodothyronine in the blood and an increase in the level of thyroid-stimulating hormone, as well as the preservation of this condition during the recovery period after the cessation of administration of the thyreostatic agent to the rats.

The declared technical result is achieved by the fact that laboratory rats are kept on a diet with a low iodine content of 20 g of the mixture per day individually for each animal for 30 days, after which the drug “Mercazolil” is administered at a dose of 2.5 mg/100 g of live weight within 21 days. Then, during the recovery period, the animals are also kept on a diet low in iodine. The rats were given water with distilled water freely available throughout the experiment.

A low iodine diet consists of the following components (per 1 kg of feed mixture):

Wheat 450 g Oats 130 g Rye 120 g Barley 60 g Buckwheat 30 g Millet 60 g Corn, grain 40 g Sunflower seeds 60 g Soy texture 50 g Vitamin supplement (in solution form) 2 drops per 10 ml of water

Literary norms for nutrient intake by laboratory rats (rat weight – 200 g):

Protein - 4 g;

Fat – 2 g;

Carbohydrates – 25 g;

Fiber – 0.5-1.0 g.

To model hypothyroidism in the studied animals, a diet was developed that sharply limited the intake of iodine into the body, but complied with the standards for the content of nutrients and macroelements.

Table 1

Low-iodine diet for experimental modeling of hypothyroidism in laboratory rats

Component name Proportion of components per 1 kg of feed mixture, % Number of components per 1 kg of feed mixture, g I content, µg Wheat 45% 450 49.5 Oats 13% 130 14.3 Rye 12% 120 13.2 Barley 6% 60 6.6 Buckwheat 3% thirty 5.3 Millet 6% 60 6.6 Corn, grain 4% 40 4.4 Sunflower seeds 6% 60 6.6 Soy texture 5% 50 5.5 Vitamin supplement* Total in 1 kg of feed mixture: 112

Note * - the vitamin dietary supplement in the form of a solution contains the following components (in 1 ml): vitamin A – 220 IU, vitamin B1 – 0.1 mg, vitamin B2 – 0.15 mg, vitamin B6 – 0.2 mg, vitamin B12 – 1.0 mcg; vitamin D3 – 20 IU, vitamin E – 0.25 mg and D-panthenol – 0.2 mg. With water in a drinking bowl at a dose of 2 drops per 10 ml of water.

The diet we developed contains about 112 mcg of iodine per 1 kg of mixture. When feeding rats with this diet, the daily dose of iodine consumption is 2.24 mcg per animal, despite the fact that normally the diet of rats should contain iodine in an amount of at least 1.5 mg/kg of food. Consequently, the diet we developed sharply limits the intake of iodine into the body of laboratory rats.

The method is carried out as follows. For experimental modeling of hypothyroidism, laboratory rats are kept on a diet with a low iodine content of 20 g of the mixture per day individually for each animal for 30 days, after which the drug “Mercazolil” is administered at a dose of 2.5 mg/100 g of live weight for 21 day. Then, during the recovery period, the animals are also kept on a diet low in iodine. The rats were given water with distilled water freely available throughout the experiment. In this way, the nutritional intake of iodine into the body is minimized and thereby the state of iodine deficiency hypothyroidism is maintained.

Based on the results of the experiments, we can talk about the high efficiency of the developed method.

To study its effectiveness, 30 clinically healthy female white nonlinear laboratory rats with a live weight of 160-170 g were used. 3 groups of animals, 10 rats each, were formed. In the first experimental group, rats received a specially developed diet (20 g of the mixture individually for each animal once a day), which corresponded to the standards for this type of animal in terms of the content of nutrients, minerals and vitamins with a reduced iodine content in the feed (0.112 mg/kg vs. 1.5 mg/kg in control) for 51 days. In the second experimental and control groups, rats received a balanced diet (Delta Feeds - food for laboratory rats and mice R-22, BioPro JSC, Russia), corresponding to the consumption standards for laboratory rats (proteins - 4 g, fats - 2 g, carbohydrates - 25 g, fiber - 0.5-1.0 g). From the 31st day of the experiment, the rats of the first and second experimental groups were injected daily intragastrically using a metal probe with the drug “Merkazolil” crushed and dissolved in water at a dose of 2.5 mg per 100 g of animal weight for 21 days. Rats in the control group were not administered the drug. On day 52, rats from each group received blood for analysis of the levels of thyroxine, triiodothyronine and thyroid-stimulating hormone. Similar studies were also carried out on the 62nd day of the experiment, while the rats continued to be kept on a diet low in iodine until the end of the experiment.

During an external examination of the animals in the experimental groups on day 52, nonspecific clinical manifestations of pathology in the body were observed, such as dullness and dullness of the hair, lethargy and decreased appetite. Such changes were not observed in animals from the control group. The animals of the first and second experimental groups developed hypothyroidism, which was confirmed by the results of biochemical studies.

table 2

Hormonal parameters of blood serum of laboratory rats on the 52nd day of the experiment

Indicators, ng/ml Control group 1st experimental group 2nd experimental group T3 1.30±0.14 0.93±0.13 0.95±0.12 T4 43.70±4.22 5.25±0.55* 5.36±0.41* TSH 1.73±0.20 8.75±0.55* 8.53±0.37*

*P≤0.05

From the data presented in Table 1, it follows that in animals of the first and second experimental groups there was a decrease in thyroxine content by 87.99% and 87.73%, respectively, an increase in TSH content by 405.78% and 393.06%, respectively, in while in animals from the control group the average thyroxine content was 43.70 ng/ml, the average TSH content was 1.73 ng/ml.

Table 3

Hormonal parameters of blood serum of laboratory rats on the 62nd day of the experiment

Indicators, ng/ml Control group 1st experimental group 2nd experimental group T3 1.34±0.11 0.98±0.08 1.12±0.11 T4 45.20±1.18 13.58±0.62* 39.64±2.01* TSH 1.66±0.17 5.24±0.27* 2.75±0.19*

*P≤0.05

The data presented in Table 2 indicate a tendency towards spontaneous normalization of thyroid function on the 11th day after cessation of administration of the thyreostatic agent, although the state of hypothyroidism persists. At the same time, in the first experimental group, which continued to be kept on a diet low in iodine, a more pronounced state of hypothyroidism was observed. Thus, the level of thyroxine in the first experimental group was 65.74% lower compared to the second experimental group and 69.96% lower than the control group. The level of thyroid-stimulating hormone in the first experimental group was 90.55% higher than in the second experimental group and 215.66% higher than in the control group.

No statistical data on significant differences were found when comparing other blood parameters in the experimental and control groups; their changes did not go beyond the physiological norm.

Thus, the presented method is an effective method for experimental modeling of hypothyroidism and minimizes the intake of iodine into the body of laboratory rats along with food. This method is the most suitable for studying the effectiveness of iodine-containing drugs. This will make it possible to develop new effective methods for the prevention and treatment of hypothyroidism resulting from iodine deficiency in the body.

Literature:

1. Antipov A.A., Deltsov A.A. Efficacy of new complex iodine-containing drugs in the pharmacocorrection of experimental hypothyroidism in rats // Veterinary medicine, zootechnics and biotechnology. 2020. No. 5. pp. 42-48.

2. Berezov T.T., Korovkin B.F. Biological chemistry: Textbook. – 3rd ed., stereotypical. – M.: OJSC “Publishing House “Medicine”, 2008. – 704 p.

3. Deltsov A.A., Rodkina O.R., Belova K.O. Assessment of chronic toxicity parameters of the complex drug "Abiovit" // Veterinary, zootechnics and biotechnology. 2022. No. 6. P. 38-45.

4. Kamilov F.Kh., Ganeev T.I., Kozlov V.N. Choice of method of application and dose of thiamazole for modeling hypothyroidism in laboratory rats // Biomedicine. 2018. No. 1. P. 59-70.

5. Ushakov A.S., Miroshnikov S.A., Rakhmatullin Sh.G., Chernov K.S. The influence of different levels of diet on the metabolism of iodine in animals // Bulletin of beef cattle breeding. 2016. No. 4(96). pp. 118-126.

Claims (3)

1. A method of experimental modeling of hypothyroidism in laboratory rats, which consists in the fact that laboratory rats are kept on a diet with a low iodine content of 20 g of the mixture per day individually for each animal for 30 days, after which the drug “Mercazolil” is administered at a dose of 2, 5 mg/100 g live weight for 21 days, then during the recovery period the animals are also kept on a low-iodine diet, with the low-iodine diet consisting of the following components per 1 kg of feed mixture: Wheat 450 g Oats 130 g Rye 120 g Barley 60 g Buckwheat 30 g Millet 60 g Corn, grain 40 g Sunflower seeds 60 g Soy texture 50 g Vitamin supplement 2 drops per 10 ml of water 2. The method according to claim 1, characterized in that they use a vitamin dietary supplement in the form of a solution containing the following components in 1 ml: vitamin A - 220 IU, vitamin B ₁ - 0.1 mg, vitamin B ₂ - 0.15 mg , vitamin B ₆ – 0.2 mg, vitamin B ₁₂ – 1.0 mcg; vitamin D ₃ – 20 IU, vitamin E – 0.25 mg and D-panthenol – 0.2 mg.